Why is Coyote Starrk underrated & underestimated.?

I wanna know why ppl underrate him.I am sick of ppl saying "Ulquiorra should be the primera instead of Starrk".cuz that is untrue.Oh yeah Plus ppl underrate him cuz he was killed by a shikai big deal its as deadly as a bankai or two.So can someone tell me why hes underrated.